Cardiovascular System: Blood Chapter 11 2013

1. Cardiovascular System: Blood Chapter 11 2013

2. Blood has several important functions and unique physical characteristics. • 1. Transporting dissolved gases, nutrients, hormones and metabolic wastes. • 2. Regulating the pH and ion composition of interstitial fluids throughout the body • 3. Restricting fluid losses at injury sites. • 4. Defending against toxins and pathogens • 5. Stabilizing body temperature.

3. Blood is made up of plasma and formed elements. • Temperature: roughly 38oC (100.4oF) • Viscosity: 5X more viscous as water = more sticky, more cohesive and resistant to flow. • pH: slightly alkaline with pH between 7.35 and 7.45

4. Plasma, contains significant quantities of plasma proteins. • 3 main types • Albumin = majority. Maintains osmotic pressure of plasma • Globulins: include antibodies and transport proteins • Fibrinogen: functions in blood clotting. Liver synthesizes most of the plasma proteins.

5. Red Blood Cells • 99% of the formed elements in plasma • Measured by hematocrit or % of whole blood volume occupied by formed elements. • Males have 5.4 million RBC’s / microliter • Females have 4.8 million RBC’s/ microliter

7. RBC’s Structure • Biconcave disc allows for large surface area for diffusion. • Flexible to squeeze through narrow capillaries • During their formation, RBCs lose most of their organelles including mitochondria • Don’t divide or synthesize any proteins. • Formed in the red bone marrow through erythropoiesis

8. Erythropoietin (EPO) stimulates the formation of RBC’s • Released by the kidneys when tissues are exposed to low oxygen levels. • EPO is released • During anemia, • When blood flow to the kidneys declines, • When oxygen content of the air in the lungs declines • When the respiratory surfaces of the lungs are damaged.

10. Hemoglobin • Hb = 95% of an RBCs proteins • Binds oxygen to an iron ion • Iron + oxygen give the blood a bright red color • Dark color when oxygen is not bound. • A low hematocrit, or a reduced oxygen-carrying capacity is a condition called anemia. • Anemia causes muscle fatigue, weakness, and a general lack of energy

11. Abnormal Hemoglobin • Read about thalassemia and sickle cell anemia on page 385 of your book.

12. ABO blood types and Rh system are based on antigen-antibody responses. • The presence of absence of specific surface antigen in RBC membranes determines your blood type • There are four blood types.

15. Hemolytic Disease of the Newborn • Sometimes the Rh factor of the fetus is different than the mother. • If the mother is Rh- and her child is Rh+, there is a chance that during delivery, the fetal and maternal blood may mix, exposing the mother to the Rh antigens of the baby. The mother will begin to produce anti-Rh antibodies. • These antibodies will cross the placenta and attach the RBC’s of the next Rh+ fetus, hemolyzing them.

17. White blood cells contribute to the body’s defenses • WBC’s = leukocytes • Larger than RBC’s • Have a nucleus and other organelles • Lack hemoglobin. • Defend the body against pathogens, remove toxins, wastes and abnormal or damaged cells.

18. WBC circulation and movement • Four characteristics • All are capable of amoeboid movement • All can migrate out of bloodstream through process of diapedesis • All are attracted to specific chemical stimuli (positive chemotaxis) • Neutrophils, eosinophils, and monocytes are capable of phagocytosis

19. Types of WBC’s • Neutrophils: first to arrive at an injury • Attack bacteria by phagocytosis • Short life span (hours) • Forms pus at the wound • Eosinophils • Attack objects coated with antibodies • Increase in numbers during a parasitic infection or allergic reaction • Basophils • Small cells that accumulate in damaged tissues where they release heparin and histamine.

20. Monocytes • Large cells • Aggressive phagocytes • Release chemicals that draw other WBC’s to injury • Lymphocytes • Migrate between the blood stream and tissues • Do not use phagocytosis • Some secrete antibodies • May be active during a viral infection.

21. Platelets function during clotting process • One of the formed elements of the blood • Formed as cell fragments from megkaryocytes in red bone marrow • Initiate clotting process and help close injured blood vessels

23. Hemostasis involves vascular spasm, platelet plug formation, and blood coagulation • Hemostasis is the process that halts bleeding and prevents the loss of blood through the walls of damaged vessels. At the same time it also establishes a framework for tissue repairs.

24. Phases of Hemostasis • 1. Vascular Phase • Cutting the wall of a blood vessel triggers the contraction of the smooth muscles • Called vascular spasm • Lasts about 30 min. • 2. Platelet Phase • Platelets begin to attach to sticky endothelial surfaces within 15 seconds forming a platelet plug. • 3. Coagulation Phase • Begins at least 30sec after injury • Involves a complex series of steps leading to a blood clot

25. The Clotting Process • Cannot occur if plasma doesn’t contain clotting factors • During clotting phase these proteins interact in sequence or cascade • Extrinsic pathway begins in the wall of the blood vessel • Intrinsic pathway begins in the blood stream • Common pathway-both process join here through the activation of Factor X

27. Calcium ions and vitamin K affect almost every aspect of the clotting process. • All three pathways require the presence of calcium ions so any disorder that lowers plasma calcium ion concentration will impair blood clotting • Vitamin K must be present for the liver to synthesize four of the clotting factors so a deficiency of vitamin K inactivates the clotting system.